Standard aerosol valve and gasket assemblies for dispensing pressurized product from a container have an inherent structural problem which limits the flow rate of product out of the container and through the valve stem. As is well known, the gasket which seals the conventional radial opening of the spring biased valve in the valve housing of conventional aerosol valves also seals the valve stem with the mounting cup of the container limiting the diameter of the opening relative to the valve stem extending through the gasket. The valve stem is provided with both an axial and a radial opening for dispensing product from the container. When the valve stem is pushed down by a user against a spring bias, the radial opening which is initially blocked by the gasket comes into fluid communication with the product in the container which is then permitted to flow through the radial opening and out the valve stem to the environment. Once the user releases the valve stem, the valve stem is biased back into a closed position with the radial opening blocked by the mounting cup gasket.
The structural problem is two-fold, first the radial opening in the side of the valve stem must be smaller than the thickness of the gasket so that the opening is adequately covered in the closed valve position, otherwise there is a substantial risk of the product being able to escape even when the valve is closed by leakage through the radial opening. The general thickness of a conventional gasket is in the range of 1.02 mm-1.52 mm (0.04-0.06 in.), so the radial openings must be substantially within this range. This along with tolerances necessary to ensure complete closure of the valve limits the size of the radial opening. Secondly, the larger the radial opening is on the upper portion of the valve stem where it is located in such conventional valve stems, the more the structural integrity of the valve stem is affected. If the opening is too large the valve stem when subjected to axial and radial forces during depression by a user can fail and break, bend or otherwise permanently damage the valve stem. Such restrictions in the size of the radial opening in the stem make it difficult to obtain high flow rates of product and a highly viscous product such as toothpaste cannot be dispensed without a sufficiently large passage in the valve stem.
Similarly, in other applications such as bag-on-valve assemblies, such valve stem openings create the same or similar structural issues. Collapsible and highly flexible product bags or pouches have become common in different industries for containing a variety of food, beverage, personal care or household care or other similar products. Such product bags can be used alone to allow a user to manually squeeze and dispense a product from the bag or the product bags may be utilized in combination with a pressurized can and product, for example an aerosol. Such product bags and valves contained in and used with aerosol cans are generally referred to in the aerosol dispensing industry as bag-on-valve (BOV) technology. These product bags, valves and cans may be designed to receive and dispense a desired product in either a liquid or semi-liquid form which have a consistency so as to be able to be expelled from the valve or outlet when desired by the user.
Bag-on-valve technology is known to utilize a product dispenser, such as a can, which has the collapsible product bag inserted therein prior to filling of the bag with a product. The bag is initially flat and inserted axially into the can usually in a rolled up manner and having a filling/dispensing valve communicating with the inside of the product bag. The valve is affixed as in the conventional valve described above to a mounting cup portion of the valve and the mounting cup is crimped to the can. During a final manufacturing phase the product bag is filled with the desired product.
In the filling process, a desired product is inserted into the product bag via the two-way valve by appropriate filling means. When the bag is filled by the filling mechanism, the product bag expands inside the can. At some point in the manufacturing process, the can is provided with a pressurized gas in order to assist in squeezing the bag to expel the contents thereof as is well known in the art. Many factors influence the expulsion of the contents or product from the can out of the valve into the environment. The valve is a key component, which has lead to the design of multiple valve configurations for different applications.
Typically, bag-on-valve applications have used valves that have two components—a valve housing and a valve stem. In most applications, the valve housing engages with a mounting cup of a can, attaches to a bag that holds the product, and provides the framework for the valve stem. The valve stem usually interacts with the valve housing through the use of a spring. The spring allows the valve stem to move relative to the valve housing to open and close the valve. Typically, when the valve is opened, product flows from the product bag, to and through the valve housing, then through a passage in the valve stem, and finally into the environment. The passage is normally limited in size and shape based on the sealing of the passage by the upper gasket that is used to seal the valve housing to the mounting cup.
An issue associated with the bag-on-valve technology is control of the volume flow of the product contents of the bag from the system to the environment. This issue is especially compounded due to the different viscosities of the various products which manufacturers dispense from such bag-on-valve containers. The various product contents include liquids, creams, foams, gels, aerosols, colloids, and various other substances. Handling the flow of a highly viscous substance such as for instance, toothpaste is particularly difficult in both conventional and bag-on-valve applications where the aerosol dispensing radial passages are particularly small in the 1.02 mm-1.52 mm (0.04-0.06 in.) range and there is no structural feasibility to make these holes larger with conventional valve structures. The problem is to be able to accommodate larger dispensing openings in the valve beyond the 1.02 mm-1.52 mm (0.04-0.06 in.) range in order to accommodate higher flow rates and more viscous product.
The present invention addresses the required increased flow rate necessary in some bag-on-valve applications. In some aerosol applications, however, the bag-on-valve containers may not be feasible due to volume constraints of the container and cost considerations even though it may be undesirable to mix the propellant gas with the product material. In these instances immiscible gases, such as nitrogen or carbon dioxide may be preferred. The present invention provides for liquefied propellants or compressed gas such as air, nitrogen or carbon dioxide to be used and further may provide metered doses of product as required in some aerosol applications.